Figure 11. The catalytic module requires interaction with the NOT module for full activity in tethering assays. (A and C) Tethering assays were performed as described in Figure 9A with POP2 or CCR4 (wild-type or mutants). Firefly luciferase activity was normalized to that of Renilla luciferase and set to 100 in the cells expressing the λN-HA peptide. (B and D) western blot showing the expression level of the protein fragments and mutants tested.